Carburetion



April 25, 944 F. c. Mmm4 TAL 2,347,427

Y cARBUREToN 2 sheets-sheet 1 Filed Aug. 5, 1940 TTQENEY Apk@ 25, 1944. F; C; MOCK TAL 2,347,427

CARBURETION Filed Aug. 3,' 1940 l 2 sneetsrsheet 2 IN VEN TOR m'etrical mixture delivery Patented Apr. 25,- `1944 UNITED sfm'rlzs` iurrlfzlv'r y omer.

oAnBUnErioN Frank C. Mock and Emil 0. Wirth, South Bend, Ind., assignors to Bendix Aviation Corporation, South'Bend, Ind., a corporation of Delaware application August s, 1940, serial No. 350,516

1 claims. (ci. 12aurl This inventionrelates generally to carburetors and more particularly to improvements in induction passages for multiple venturi carburetors.

In many multi-cylinder .internal combustion engines, the intake manifold distributes and delivers the fuel mixture unevenly among the various cylinders. This uneven distribution of fuel mixture bythe intake manifold causes some cylinders to receive a richer mixture than others resulting` in well known operating faults suoli as excessive fuel consumption, decrease in power, and in extreme cases, uneven running of the engine.

tributesto the uneven mixture delivery. However, it has been discovered that the problem can be solved by modifying the induction passage of the carburetor to deliver iuel mixture etrically to the inlet of the intake manifold to coinpensate for all of the factors, taken collectively, causing uneven distribution. lt is therefore an important object of the invention to provide a carburetor having an induction passage that will supply an asymmetrical fuel mixture to the intake manifold to correct errors of mixture distribution.

In multiple venturi carburetors. the position f of the'several venturis relative to each other and -tothe throttle barrel or mixture outlet largely governs the axis ofthe fuel spray relative to the air column in the induction passage and it has been found that by offsetting one of these parts relative to the others an asymmetrical fuel spray is produced which provides the desired asymto the inlet of the intake manifold.

It is, therefore, another important object of the invention to provide a carburetor of this character wherein at least one of the component parts of the induction passage which govern the axis of the fuel spray is offset relative to the other parts whereby asymmetrical fuel mixture delivery to the intake manifold is eiected.

It is still another object of the invention to provide a device of this character wherein at least the outlet of an element or part of the induction passage is olset with' respect to the other elements.

Otherv objects and advantages of the invention will appear from the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a vertical section through a carburetor embodying the invention; f

Figure 2 is a partial plan view of an intake mani-fold attached to an engine block and adapted to have a downdraft carburetor attached thereto; said view includes the forward end of the manifold; Y f

Figure 31s a partial horizontal section through the induction passage above the large venturi showing a Amodified embodiment -of the invention;

Figure l is a partial vertical section throne a carburetor induction passage showing another modication of the invention; and

' Figure 5 is a similar view taken at right angles lets 2l attached in the usual manner to block -23 of an engine. The carburetor induction passage comprises an air inlet It controlled by an offset choke valve 2li mounted on a shaft 22 and controlled by any suitable manual ,or automatic means, a small or primary venturi 2t, a large or secondary Vventuri 25, a throttle barrel or mixing chamber 28, and a mixture outlet Bil. A throttle valve 32, mounted on throttle shaft 34, controls the throttle barrelln the known manner.

A fuel chamber 36 in the main body section has-the usual iloat 38 mounted by any known means (not shown) vfor controlling the level L.L of fuel in the chamber. Idllng Jet 40 of known construction is supplied with idling fuel Vfrom chamber 36 by means of communicating passages 42, S4 and 46, the latter having the usual idling tube A8 therein. The lower end of passageV 4B communicates with an acceleration well 50 v The air inlet passage 52 of known construction and Uperation is received. The main fuel nozzle l2' is positioned toward the forward end of the engine, and is secured in the bore by a plug M screwed into a boss formed integral with a wall of the main body section l2. The plug is provided with a metering orifice itreceiving fuel from the lower part of fuel chamber 3l. Air is bled to the nozzle l2 from an air bleed It in the known manner. In the embodiment of the invention disclosed in Figure l, the small venturi 24 and throttle barrel 28 are concentric having a common axis A-A which is also the axis of the the manifold I1. To produce an asymmetrical fuel spray in the induction passage and'deliver same asymmetrically to the inlet ll, the large venturi 26 is offset, its axis B being illustrated as to the right or rear of axis A-A in Figure 2. I8 is also concentric with the small venturi and throttle barrel but this passage has little eifect onthe symmetry of the fuel mixture in the carburetor.

In Figure 3, the large venturi 2l is also onset from a concentric venturi and'throttle barrel but the position of the axis of the large venturi is mixture inlet. of 'i modified, being indicated at c, said axis c being diagonally rearward oi' axis A and away from the engine block.

In the modified embodiment of the invention shown in Figure 4, similar parte are given the same reference numerals as those in Figure 1 plus |00, the air `inlet passage III, the primary venturi |24 and the secondary venturi |20 being concentric with a common axis Ai-As In this embodiment of the invention. the throttle barrel is offset, the axis being indicated at T T.

. In the modification ilar parts are given the same reference numerals as in Figure 1 plus 2". The air inlet 2li. large venturi 226 and throttle barrel 228 are concentric with respect to common axis iis-Ae. In this embodiment. the small venturi iisis laterally or transversely offset, its axis being at B-S. as

shown also in Figures.

n While the invention'has been shown in connection with a double venturi down draft carburetor. itis to be understood that it may also be illustrated by Figure 5, sim- I deliver fuel to the venturi and mixture the secondary venturi being oil'set'relative thereto.

its attendant advantages will be understood from the foregoing description. and it will be apparent that various changes may be made in the fonn, construction and arrangement of the parts without departing from the spiritV and scope of the invention'or sacrlncing all of its material advantages, the forms hereinbefore described being merely preferred embodiments thereof.

We claim:

1. in a downdraft carburetor, sage having a concentric air inlet. primary venturi, and throttle barrel, and a secondary venturi axially oifset relative thereto, the section of the induction passage containing the venturis being of constant effective area.

2. In a carburetor, an induction passage having an air inlet. a primary venturi. a secondary venturi, and a mixture passage, the section of the induction passage containing said venturis being of constant en'ective area, and a fuel nomle to primary venturi. the primary passage being concentric and '3, In a charge forming device havingan induction passage including a primary venturi. a 'secondary venturi. and a mixing chamber, the section of the induction passage in which the venturis are disposed being of constant edective area, and means to deliver fuel to one op the venturis, the primary venturi and mixing chamber being concentric, the 4secondary venturi having its outlet eccentric relative. to the ing chamber.

4. In an induction passage for a charge forming device, a small venturi, a mixing chamber coaxial therewith, and a large venturi offset relative to said small venturi and mixing chamber,

the section ofthe induction passage in which the embodied in other types including updraft or horizontal draft carburatore `or those having more than two venturis. The offsetting of the fuel spray may be made in any direction or of any degree in the induction passage that will provide the desired asymmetrical fuel mixture to the inlet which will correct errors of mixture distribu-V tion to the engine cylinders. It is also to -be un derstood that while the. various parts of the induction passage that determine the axis of the fuel spray are shown in the various mrc! as be. ing axially oifset, the offsetting of the outlet of one of these parte, such for example as by tilting the small venturi relative to the axis of the large venturi. will also produce a suitable asymmetrical It is thought that the invention and many 0f venturis are located being of constant effective area duction passage having a section of constant effective area, a primary venturi. a secondary venturi concentric thereto, and a mixture chamber odset relative to the venturis. said venturis being disposed within said section of the f induction passage. t 7. In a charge' forming device having an induc- .tion passage including a large and a small venituri anda mixture chamber, the large venturi being otl'set with repect to at least one of the other parte of the induction passage. said induction passage having a portion of. constant edective area lwithin which the venturis are disposed.

' e FRANK C. MOCK.

L d EMIL O. WIRTH. l

an induction pasprimary venturi and mixs. 'In s charge :dimmi device having an indue- 

